Morphology, Phase and Chemical Analysis of Leachate after Bioleaching Metals from Printed Circuit Boards

Kamila Hyra; Paweł M Nuckowski; Joanna Willner; Tomasz Suponik; Dawid Franke; Mirosława Pawlyta; Krzysztof Matus; Waldemar Kwaśny

doi:10.3390/ma15134373

Morphology, Phase and Chemical Analysis of Leachate after Bioleaching Metals from Printed Circuit Boards

Materials (Basel). 2022 Jun 21;15(13):4373. doi: 10.3390/ma15134373.

Authors

Kamila Hyra¹, Paweł M Nuckowski², Joanna Willner³, Tomasz Suponik⁴, Dawid Franke⁴, Mirosława Pawlyta², Krzysztof Matus², Waldemar Kwaśny⁵

Affiliations

¹ Department of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian University of Technology, 18A Konarskiego Street, 44-100 Gliwice, Poland.
² Materials Research Laboratory, Faculty of Mechanical Engineering, Silesian University of Technology, 18A Konarskiego Street, 44-100 Gliwice, Poland.
³ Department of Metallurgy and Recycling, Faculty of Materials Engineering, Silesian University of Technology, 8 Krasińskiego Street, 40-019 Katowice, Poland.
⁴ Department of Geoengineering and Raw Materials Extraction, Faculty of Mining, Safety Engineering and Industrial Automation, Silesian University of Technology, 2 Akademicka Street, 44-100 Gliwice, Poland.
⁵ Department of Welding, Faculty of Mechanical Engineering, Silesian University of Technology, 18A Konarskiego Street, 44-100 Gliwice, Poland.

Abstract

The article presents the assessment of solutions and dried residues precipitated from solutions after the bioleaching process of Printed Circuit Boards (PCB) utilizing the Acidithiobacillus ferrooxidans. The obtained dried residues precipitated from bioleaching solution (leachate) and control solution were tested using morphology, phase, and chemical composition analysis, with particular emphasis on the assessment of crystalline and amorphous components. The analysis of the dried residues from leachate after bioleaching as well as those from the sterile control solution demonstrated a difference in the component oxidation-the leachate consisted of mainly amorphous spherical particles in diameter up to 200 nm, forming lacy aggregates. In the specimenform control solution larger particles (up to 500 nm) were observed with a hollow in the middle and crystalline outer part (probably Fe₂O₃, CuFeS₂, and Cu₂O). The X-ray diffraction phase analysis revealed that specimen obtained from leachate after bioleaching consisted mainly of an amorphous component and some content of Fe₂O₃ crystalline phase, while the dried residue from control solution showed more crystalline components. The share of the crystalline and amorphous components can be related to efficiency in dissolving metals during bioleaching. Obtained results of the investigation confirm the activity and participation of the A. ferrooxidans bacteria in the solubilization process of electro-waste components, with their visible degradation-acceleration of the reaction owing to a continuous regeneration of the leaching medium. The performed investigations allowed to characterize the specimen from leachate and showed that the application of complementary cross-check of the micro (SEM and S/TEM) and macro (ICP-OES and XRD) methods are of immense use for complete guidance assessment and obtained valuable data for the next stages of PCBs recycling.

Keywords: X-ray diffraction (XRD); bioleaching; high resolution transmission electron microscopy (S/TEM); metals recovery; recycling; scanning electron microscopy (SEM).

Abstract

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